Sealed refrigerant compressor and refrigeration device including same

ABSTRACT

A sealed refrigerant compressor ( 100 ) includes: a compression element ( 107 ) accommodated in a sealed container ( 101 ) and configured to compress a refrigerant; and an electric element ( 106 ) configured to drive the compression element ( 107 ). Lubricating oil ( 103 ) is stored in the sealed container ( 101 ). The lubricating oil ( 103 ) is mixed oil constituted by at least mineral oil and synthetic oil. Kinetic viscosity of the lubricating oil ( 103 ) at 40° C. falls within a range of 0.1 to 5.1 mm 2 /s, and a flash point of the lubricating oil ( 103 ) is 110° C. or more.

TECHNICAL FIELD

The present invention relates to a sealed refrigerant compressor whichuses lower-viscosity lubricating oil and has high productivity, and arefrigeration device including the sealed refrigerant compressor.

BACKGROUND ART

Highly efficient refrigerant compressors which reduce the use of fossilfuels from the viewpoint of the protection of the global environmenthave been developed in recent years. For example, in order to increasethe efficiency of the refrigerant compressors, proposed is the use oflubricating oil having lower viscosity.

For example, each of PTLs 1 and 2 discloses a specific compositioncontaining ester, as a freezer lubricating oil composition having lowviscosity, high lubricity, and excellent long term stability in a lowtemperature range. Kinetic viscosity of the lubricating oil compositionat 40° C. falls within a range of 6 to 28 mm²/s.

It is known that when the lubricating oil having lower viscosity is usedin the refrigerant compressors, abrasion, seizure, or the like occurs ata slide member constituting a slide portion. Therefore, a technique forgiving abrasion resistance to the slide member or the lubricating oilhave been proposed.

For example, PTL 3 discloses that in order to prevent abrasion, seizure,and the like at the slide member when the lubricating oil having lowviscosity is used, a piston and connecting rod constituting the slideportion are constituted by iron-based sintered materials and subjectedto a steam treatment, a steam layer is cut and removed from the surfaceof the piston, and the connecting rod is subjected to a nitridingtreatment after the steam treatment.

PTL 3 describes that it is preferable that the kinetic viscosity of thelubricating oil at 40° C. fall within a range of 3 to 10 mm²/s. PTL 3describes that: when the kinetic viscosity of the lubricating oil isless than 3 mm²/s, the viscosity of the lubricating oil when therefrigerant melts becomes low, and an oil film is not adequately held;and therefore, lubricity becomes poor, and a seal performance of acompression portion is not kept.

PTL 4 describes that in order to improve abrasion resistance of freezeroil, a predetermined amount of specific phosphorus compound is added tolubricating oil base oil. PTL 4 describes that it is preferable that thekinetic viscosity of the lubricating oil base oil at 40° C. fall withina range of 3 to 300 mm²/s.

CITATION LIST Patent Literature

PTL 1: Japanese Laid-Open Patent Application Publication No. 2006-160781

PTL 2: Japanese Laid-Open Patent Application Publication No. 2006-328275

PTL 3: Japanese Laid-Open Patent Application Publication No. 2011-021530

PTL 4: Japanese Laid-Open Patent Application Publication No. 2013-203988

SUMMARY OF INVENTION Technical Problem

That the lubricating oil having viscosity lower than lower limits of theranges of the kinetic viscosities disclosed in PTLs 1 to 4 is used asthe lubricating oil for the refrigerant compressors have been consideredrecently.

When the viscosity of the lubricating oil is lowered, volatility of thelubricating oil becomes high. Therefore, a flash point of thelubricating oil lowers as the viscosity of the lubricating oil lowers.If the flash point of the lubricating oil lowers, more extreme careagainst fire is required when handling the lubricating oil. In addition,low distillation components contained in the lubricating oil mayevaporate first, and this may increase the viscosity of the lubricatingoil. Therefore, a special storage condition is required. As above,lowering the viscosity of the lubricating oil leads to deterioration ofthe handleability of the lubricating oil. As a result, the productivityof the refrigerant compressor also deteriorates.

As is clear from the fact that PTLs 1 to 4 do not describe thedeterioration of the handleability of the lubricating oil and thedeterioration of the productivity of the refrigerant compressor due tothe deterioration of the handleability of the lubricating oil, suchdeteriorations have been discussed little.

The present invention was made to solve the above problems, and anobject of the present invention is to provide a sealed refrigerantcompressor capable of realizing high productivity even when lubricatingoil having lower viscosity is used, and a refrigeration device includingthe sealed refrigerant compressor.

Solution to Problem

To solve the above problems, a sealed refrigerant compressor accordingto the present invention includes: a compression element accommodated ina sealed container and configured to compress a refrigerant; and anelectric element configured to drive the compression element.Lubricating oil is stored in the sealed container. The lubricating oilis mixed oil constituted by at least mineral oil and synthetic oil.Kinetic viscosity of the lubricating oil at 40° C. falls within a rangeof 0.1 to 5.1 mm²/s. A flash point of the lubricating oil is 110° C. ormore.

According to the above configuration, the major component (base oil) ofthe lubricating oil is not the mineral oil but the mixed oil constitutedby the mineral oil and the synthetic oil. When mixing the mineral oiland the synthetic oil with each other, the kinetic viscosity is adjustedto fall within the above range, and the lower limit of the flash pointis adjusted to become the above value. With this, the lubricating oilhaving low viscosity and high flash point is obtained, and therefore,the deterioration of the handleability of the lubricating oil can beeffectively suppressed. On this account, by using the lubricating oil,the efficiency of the sealed refrigerant compressor can be increased. Inaddition, even when the lubricating oil having lower viscosity is used,the high productivity can be realized.

Further, the present invention includes a refrigeration device includingthe sealed refrigerant compressor configured as above. Therefore, thepresent invention can provide the refrigeration device having highperformance and high productivity.

ADVANTAGEOUS EFFECTS OF INVENTION

By the above configurations, the present invention has an effect ofbeing able to provide a sealed refrigerant compressor capable ofrealizing high productivity even when lubricating oil having lowerviscosity is used, and a refrigeration device including such sealedrefrigerant compressor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view showing one example of a typicalconfiguration of a sealed refrigerant compressor according to Embodiment1 of the present disclosure.

FIG. 2 is a schematic diagram showing one example of a typicalconfiguration of a refrigeration device according to Embodiment 2 of thepresent disclosure.

DESCRIPTION OF EMBODIMENTS

A sealed refrigerant compressor according to the present disclosureincludes: a compression element accommodated in a sealed container andconfigured to compress a refrigerant; and an electric element configuredto drive the compression element. Lubricating oil is stored in thesealed container. The lubricating oil is mixed oil constituted by atleast mineral oil and synthetic oil. Kinetic viscosity of thelubricating oil at 40° C. falls within a range of 0.1 to 5.1 mm²/s. Aflash point of the lubricating oil is 110° C. or more.

According to the above configuration, the major component (base oil) ofthe lubricating oil is not the mineral oil but the mixed oil constitutedby the mineral oil and the synthetic oil. When mixing the mineral oiland the synthetic oil with each other, the kinetic viscosity is adjustedto fall within the above range, and the lower limit of the flash pointis adjusted to become the above value. With this, the lubricating oilhaving low viscosity and high flash point is obtained, and therefore,the deterioration of the handleability of the lubricating oil can beeffectively suppressed. On this account, by using the lubricating oil,the efficiency of the sealed refrigerant compressor can be increased. Inaddition, even when the lubricating oil having lower viscosity is used,the high productivity can be realized.

In the sealed refrigerant compressor configured as above, a content ofthe synthetic oil in the lubricating oil may fall within a range of 0.1to 40.0 wt. % of an entire amount of the lubricating oil.

According to the above configuration, when the content of the syntheticoil is set to fall within the above range, the kinetic viscosity of thelubricating oil and the lower limit of the flash point of thelubricating oil can be easily adjusted to fall within theabove-described respective numerical ranges.

In the sealed refrigerant compressor configured as above, the syntheticoil may be at least one selected from the group consisting of ester oil,ether oil, polyalkylene glycol oil, and alkyl benzene oil.

According to the above configuration, by mixing the synthetic oil thatis at least one selected from the above group with the mineral oil, thekinetic viscosity of the lubricating oil and the lower limit of theflash point of the lubricating oil can be easily adjusted to fall withinthe above-described respective numerical ranges.

In the sealed refrigerant compressor configured as above, at least oneof additives that are an extreme pressure additive, an oily agent, anantifoaming agent, and a stabilizing agent may be added to thelubricating oil.

According to the above configuration, by adding such additive to thelubricating oil, the property of the lubricating oil improves, and thereliability of the sealed refrigerant compressor improves.

In the sealed refrigerant compressor configured as above, a content ofthe additive may fall within a range of 0.1 to 4.0 wt. % of the entireamount of the lubricating oil.

According to the above configuration, by adjusting the content of theadditive added to the lubricating oil within the above range, theproperties of the lubricating oil can be improved by an appropriateamount of the additive. Therefore, the reliability of the sealedrefrigerant compressor can be improved.

In the sealed refrigerant compressor configured as above, thelubricating oil may have a distillation property in which a distillationrange is 200 to 400° C.

According to the above configuration, when the distillation property ofthe lubricating oil has the above distillation range, the tendency ofthe lowering of the flash point of the lubricating oil can be suppressedmore effectively, and the stability of the lubricating oil can be madesatisfactory. As a result, the handleability of the lubricating oil canbe made more suitable.

Further, a refrigeration device according to the present disclosureincludes any one of the sealed refrigerant compressors configured asabove. With this, the refrigeration device includes the sealedrefrigerant compressor having high efficiency and high productivity, andtherefore, the present invention can provide the refrigeration devicehaving high performance and high productivity.

Hereinafter, typical embodiments of the present disclosure will bedescribed with reference to the drawings. In the following descriptionand the drawings, the same reference signs are used for the same orcorresponding members, and a repetition of the same explanation isavoided.

Embodiment 1 Configuration of Refrigerant Compressor

First, a typical example of a refrigerant compressor according toEmbodiment 1 will be specifically described with referent to FIG. 1.FIG. 1 is a schematic sectional view of a refrigerant compressor 100according to Embodiment 1.

As shown in FIG. 1, a refrigerant gas 102 is filled in a sealedcontainer 101 of the refrigerant compressor 100, and lubricating oil 103is stored in a bottom portion of the sealed container 101. In thepresent disclosure, as described below, for example, a hydrocarbonrefrigerant is used as the refrigerant gas 102, and a mixed oilconstituted by at least mineral oil and synthetic oil is used as thelubricating oil 103. An electric element 106 and a compression element107 are accommodated in the sealed container 101. The electric element106 is constituted by a stator 104 and a rotor 105. The compressionelement 107 is a reciprocating type driven by the electric element 106.

The compression element 107 is constituted by a crank shaft 108, acylinder block 112, a piston 115, and the like. The configuration of thecompression element 107 will be described below.

The crank shaft 108 is constituted by at least a main shaft 109 and aneccentric shaft 110. The main shaft 109 is press-fitted and fixed to therotor 105. The eccentric shaft 110 is formed eccentrically with respectto the main shaft 109. An oil supply pump 111 communicating with thelubricating oil 103 is provided at a lower end of the crank shaft 108.

The cylinder block 112 is made of cast iron. The cylinder block 112forms a substantially cylindrical bore 113 and includes a bearing 114supporting the main shaft 109.

The rotor 105 includes a flange surface 116, and an upper end surface ofthe bearing 114 is a thrust surface 117. A thrust washer 118 is insertedbetween the flange surface 116 and the thrust surface 117 of the bearing114. The flange surface 116, the thrust surface 117, and the thrustwasher 118 constitute a thrust bearing 119.

The piston 115 is loosely fitted into the bore 113 with a certain amountof clearance and is made of an iron-based material. The piston 115 formsa compression chamber 120 together with the bore 113. The piston 115 iscoupled to the eccentric shaft 110 by a connecting rod 122 as a couplerthrough a piston pin 121. An end surface of the bore 113 is sealed by avalve plate 123.

A head 124 forms a high pressure chamber. The head 124 is fixed to thevalve plate 123 at an opposite side of the bore 113. A suction tube (notshown) is fixed to the sealed container 101 and connected to alow-pressure side (not shown) of a refrigeration cycle. The suction tubeintroduces the refrigerant gas 102 into the sealed container 101. Asuction muffler 125 is sandwiched between the valve plate 123 and thehead 124.

A cluster 127 is connected through a lead wire 126 to the stator 104constituting the electric element 106. A terminal 128 is provided at thesealed container 101 so as to penetrate the sealed container 101 frominside to outside. The cluster 127 is coupled to the terminal 128. Withthis, electric power is supplied from a commercial power supply (notshown) to the electric element 106.

The type of the refrigerant gas 102 used in the refrigerant compressor100 according to the present disclosure is not especially limited, butthe above-described hydrocarbon refrigerant is preferably used. Specificexamples of the hydrocarbon refrigerant include R290 (propane), R600a(isobutane), R600 (butane), and R1270 (propylene), but the hydrocarbonrefrigerant is not especially limited. Typical examples of thehydrocarbon refrigerant include R600a and R290.

As described below, the refrigerant compressor 100 according to thepresent disclosure uses the lubricating oil 103 having low viscosity anda high flash point. As described above, the lubricating oil 103 is themixed oil constituted by the mineral oil and the synthetic oil. Therefrigerant gas 102 is used in a refrigerant circuit (refrigerationcycle; see Embodiment 2) including the refrigerant compressor 100. Therefrigerant gas 102 and the lubricating oil 103 exist in the sealedcontainer 101 in a state where the refrigerant gas 102 and thelubricating oil 103 can contact and be mixed with each other. Therefore,the refrigerant gas 102 and the lubricating oil 103 can be regarded asconstituting a working medium for the refrigeration cycle. The workingmedium for the refrigeration cycle contains a refrigerant component anda lubricating oil component and may further contain other components.

In the refrigerant compressor 100 according to the present disclosure,resin members are included as members accommodated in the sealedcontainer 101. The resin members are not especially limited as long asthe resin members are constituted by at least resin, i.e., polymer.Typical examples of the resin members include the suction muffler 125,an insulating member attached to the electric element 106, and thecluster 127.

These resin members may be constituted only by resin (polymer). However,for example, the resin members may be constituted by composite materialscontaining a different material, such as a fibrous material or a filler,in addition to the resin. The cluster 127 is, for example, a member madeof polyester resin containing glass fibers. Similarly, the suctionmuffler 125 is, for example, a member made of polyester resin containingglass fibers.

The resin (polymer) constituting the resin member is not especiallylimited. Specific examples of the resin (polymer) include polyesterresin (such as polyethylene terephthalate (PET) and polybutyleneterephthalate (PBT)), polyamide (PA), polyphenylene sulfide (PPS), andliquid crystal polymer (liquid crystal polyester (LCP)). Since suchresin excels in heat resistance, refrigerant resistance, oil resistance,and the like, such resin is preferably used as the material of the resinmember accommodated in the sealed container 101.

The resin material constituting the resin member is only required to beone type of resin but may be a polymer alloy (polymer blend) prepared bysuitably combining two or more types of resin. Further, a known additivemay be contained in the resin constituting the resin member.

As described above, examples of the different material contained in theresin member include the fibrous material and the filler. Examples ofthe fibrous material include an aramid fiber, a nylon fiber, a polyesterfiber, a glass fiber, and a carbon fiber. However, the fibrous materialis not especially limited. Only one type of fibrous material may beused, or two or more types of fibrous materials may be used suitably incombination. The filler is only required to be in the form of particlesor powder, but may be in the form of short fibers. In some cases, thefibrous material is regarded as the filler. Specific examples of thefiller include inorganic fillers, such as silica, silicate, clay,plaster, alumina, titanium dioxide, talc, and carbon black. However, thefiller is not especially limited.

One example of operations of the refrigerant compressor 100 according tothe present disclosure will be described below. First, electric power issupplied from a commercial power supply (not shown) through the terminal128 and the cluster 127 to the electric element 106, and this rotatesthe rotor 105 of the electric element 106. The rotor 105 rotates thecrank shaft 108, and an eccentric motion of the eccentric shaft 110drives the piston 115 through the connecting rod 122 as the coupler andthe piston pin 121.

The piston 115 reciprocates in the bore 113, and with this, therefrigerant gas 102 introduced into the sealed container 101 through thesuction tube (not shown) is sucked from the suction muffler 125 andcompressed in the compression chamber 120. In accordance with therotation of the crank shaft 108, the lubricating oil 103 is suppliedfrom the oil supply pump 111 to respective slide portions. Thus, theslide portions are lubricated, and the lubricating oil 103 serves as aseal between the piston 115 and the bore 113.

Configuration of Lubricating Oil

In recent years, in order to further increase the efficiency, measuresare being taken, i.e., for example, oil having lower viscosity is usedas the lubricating oil 103. As described above, in the presentdisclosure, the lubricating oil 103 used in the refrigerant compressor100 is the mixed oil constituted by at least the mineral oil and thesynthetic oil. The kinetic viscosity of the lubricating oil 103 (mixedoil) at 40° C. falls within a range of 0.1 to 5.1 mm²/s and isrelatively lower than that of conventional oil. In addition, the flashpoint of the lubricating oil 103 is 110° C. or more.

The lubricating oil 103 according to the present disclosure contains themineral oil as a major component and the synthetic oil as a subcomponentand may contain other components. Therefore, the lubricating oil 103according to the present disclosure is a lubricating oil compositioncontaining the mineral oil and the synthetic oil. The content (contentrate) of the mineral oil in the lubricating oil 103 is not especiallylimited, and the content of the mineral oil in the lubricating oil 103is only required to be set such that the mineral oil is regarded as the“major component” in the entire lubricating oil 103 (lubricating oilcomposition). Further, the content (content rate) of the synthetic oilin the lubricating oil 103 is not especially limited, and the content ofthe synthetic oil in the lubricating oil 103 is only required to be setsuch that: the synthetic oil is regarded as the “subcomponent” in theentire lubricating oil 103 (lubricating oil composition); and thecontent of the synthetic oil is smaller than the content of the mineraloil.

When the entire amount of the lubricating oil 103 is regarded as 100 wt.%, the content of the synthetic oil as the subcomponent is only requiredto fall within, for example, a range of 0.1 to 40.0 wt. %, preferably arange of 1 to 35 wt. %, more preferably a range of 5 to 25 wt. %.Further, the content of the mineral oil as the major component in thelubricating oil 103 is only required to be larger than the content ofthe synthetic oil. For example, when the content of the synthetic oil is40.0 wt. % or less of the entire amount of the lubricating oil 103 asdescribed above, the content of the mineral oil is only required toexceed 40.0 wt. % of the entire amount of the lubricating oil 103 andmay be, for example, 50 wt. % or more.

In the present disclosure, the synthetic oil is mixed (blended) with themineral oil such that the viscosity of the lubricating oil 103 islowered, and in addition, the flash point of the lubricating oil 103 isprevented from lowering. Therefore, when the content of the syntheticoil is set to fall within the above range, the kinetic viscosity of thelubricating oil 103 and a lower limit of the flash point of thelubricating oil 103 can be easily adjusted to fall within theabove-described respective numerical ranges.

The types of the mineral oil and synthetic oil constituting thelubricating oil 103 are not especially limited. General examples of themineral oil include paraffin mineral oil and naphthenic mineral oil. Inthe present disclosure, the paraffin mineral oil or the naphthenicmineral oil may be used, or a mixture of the paraffin mineral oil andthe naphthenic mineral oil may be used. Further, plural types ofparaffin mineral oils having different physical properties may be usedin combination. Similarly, plural types of naphthenic mineral oilshaving different physical properties may be used in combination.Further, a mixture of a combination of different paraffin mineral oilsand a combination of different naphthenic mineral oils may be used.

Specific examples of the synthetic oil include polyalphaolefin oil,alkyl benzene oil, ester oil, ether oil, polyalkylene glycol oil,fluorinated synthetic oil, and silicon synthetic oil. However, thesynthetic oil is not especially limited. Only one type of synthetic oilmay be selected and mixed with the mineral oil, or a combination ofplural types of synthetic oils may be mixed with the mineral oil.

In the present disclosure, it is preferable to use at least one selectedfrom the group consisting of ester oil, ether oil, polyalkylene glycoloil, and alkyl benzene oil. By mixing at least one of these syntheticoils with the mineral oil, the kinetic viscosity of the lubricating oil103 and the lower limit of the flash point of the lubricating oil 103can be easily adjusted to fall within the above-described respectivenumerical ranges. Further, depending on the type of the synthetic oil,properties other than the kinetic viscosity and the lower limit of theflash point can be given to the lubricating oil 103. For example, whenester oil having polarity is selected as the synthetic oil and mixedwith the mineral oil, the polarity can be given to the lubricating oil103.

In the present disclosure, the lubricating oil 103 is manufactured bymixing at least the mineral oil and the synthetic oil with each other.With this, as described above, the kinetic viscosity of the lubricatingoil 103 at 40° C. is adjusted to fall within a range of 0.1 to 5.1mm²/s, and the flash point of the lubricating oil 103 is adjusted to110° C. or more. The kinetic viscosity of the lubricating oil 103 at 40°C. is not especially limited as long as it falls within the above range.However, a preferable example is that the kinetic viscosity of thelubricating oil 103 at 40° C. falls within a range of 0.1 to 4.5 mm²/s,and a more preferable example is that the kinetic viscosity of thelubricating oil 103 at 40° C. falls within a range of 0.1 mm²/s or moreand less than 3.0 mm²/s. In the present disclosure, the kineticviscosity is measured based on JIS K2283.

If the kinetic viscosity of the lubricating oil 103 at 40° C. exceeds5.1 mm²/s, this does not mean that the viscosity of the lubricating oil103 is lowered. Therefore, the effect of the increase in the efficiencyby the lowering of the viscosity cannot be adequately obtained. Incontrast, if the kinetic viscosity of the lubricating oil 103 at 40° C.is less than 0.1 mm²/s, the lubricating effect of the lubricating oil103 may not be adequately obtained.

Similarly, in the present disclosure, the lower limit of the flash pointof the lubricating oil 103 is not especially limited as long as it is110° C. or more. However, a preferable example is 120° C. or more, and amore preferable example is 150° C. or more. In the present disclosure,the flash point is measured based on JIS K2265. If the lower limit ofthe flash point of the lubricating oil 103 is less than 110° C., moreextreme care against fire is required when handling the lubricating oil103. In addition, if a special storage condition is not satisfied, theviscosity of the lubricating oil 103 may increase over time. Therefore,the handleability of the lubricating oil 103 deteriorates.

Specifically, if the flash point of the lubricating oil 103 lowers, theamount of low distillation components contained in the lubricating oil103 increases. Therefore, if the lubricating oil 103 is stored under anormal condition, the low distillation components contained in thelubricating oil 103 may evaporate first, and this may increase theviscosity of the lubricating oil 103 over time. The general lubricatingoil 103 is stored under a low-vacuum and high-temperature condition,such as a 10⁻² Pa atmosphere and a temperature range of 40 to 60° C.However, if the flash point of the lubricating oil 103 is low, the lowdistillation components evaporate under such low-vacuum andhigh-temperature condition, and this increases the viscosity over time.Therefore, a special storage condition using a chemical filter isrequired.

It is more preferable that in addition to the range of the kineticviscosity of the lubricating oil 103 at 40° C. and the lower limit ofthe flash point of the lubricating oil 103, a predetermined distillationproperty be satisfied. Specifically, it is preferable that thelubricating oil 103 according to the present disclosure have adistillation property in which a distillation range is 200 to 400° C.(i.e., a distillation property in which an initial boiling point is 200°C., and an end point is 400° C.). In the present disclosure, thedistillation property is measured based on JIS K2254.

Since the mineral oil is basically a mixture of many types of oilysubstances, the mineral oil has a wide variety of distillationproperties. However, since the synthetic oil is basically constituted byone type of synthetic compound (or several types of syntheticcompounds), one distillation property is specified (or severaldistillation properties are specified). Therefore, by mixing thesynthetic oil with the mineral oil, the distillation property of thelubricating oil 103 that is the mixed oil can be adjusted to fall withinthe above distillation range. It should be noted that the mineral oilmay be refined so as to also fall within the above distillation rangeaccording to need.

In the present disclosure, when the lubricating oil 103 satisfies acondition that is the distillation property in addition to basicconditions that are the range of the kinetic viscosity at 40° C. and thelower limit of the flash point, the amount of the low distillationcomponents contained in the lubricating oil 103 can be made smaller.Therefore, the tendency of the lowering of the flash point of thelubricating oil 103 can be suppressed more effectively, and thestability of the lubricating oil 103 can be made satisfactory. As aresult, the handleability of the lubricating oil 103 can be made moresuitable.

As described above, the lubricating oil 103 according to the presentdisclosure is the lubricating oil composition constituted by the mineraloil and the synthetic oil and may contain a component other than themineral oil and the synthetic oil. Specific examples of such componentinclude various additives known in the field of the lubricating oil 103.

The additive is not especially limited but is, for example, at least oneof an extreme pressure additive, an oily agent, an antifoaming agent,and a stabilizing agent. By adding such additive to the mixed oilconstituted by the mineral oil and the synthetic oil, the property ofthe lubricating oil 103 improves, and the reliability of the refrigerantcompressor 100 improves.

The amount of the additive added (the content of the additive) is notnot especially limited. In the present disclosure, the amount of theadditive added is only required to fall within a range of 0.1 to 4.0 wt.% of the entire amount of the lubricating oil 103. If the content of theadditive is less than 0.1 wt. % of the entire amount of the lubricatingoil 103, the amount of the additive added may be too small, andtherefore, the effect of the additive may not be adequately obtained,although it depends on the type of the additive. In contrast, if thecontent of the additive exceeds 4.0 wt. % of the entire amount of thelubricating oil 103, the effect corresponding to the amount of theadditive added may not be obtained, although it depends on the type ofthe additive. In addition, since the content of the additive isexcessive, this may influence other physical properties of thelubricating oil 103.

In the present disclosure, a typical example of the additive is thestabilizing agent. By adding the stabilizing agent, the physicalproperties of the lubricating oil 103 having the low viscosity and thehigh flash point can be satisfactorily stabilized. In the presentdisclosure, examples of the stabilizing agent include an acid capturingagent and fullerene.

The acid capturing agent is used to prevent a case where the base oil(i.e., the mixed oil constituted by the mineral oil and the syntheticoil) is deteriorated by water or oxygen, and this increases the acidvalue. By suppressing the deterioration of the mixed oil (base oil) bythe addition of the acid capturing agent, the kinetic viscosity of thelubricating oil 103 at 40° C. can be effectively prevented from fallingoutside the above range.

The specific type of the acid capturing agent is not especially limited,and a known acid capturing agent can be suitably used. Since thefullerene has an effect of suppressing the lowering of the flash pointof the lubricating oil 103, the fullerene can be used as a “flash pointlowering suppressing agent.” Therefore, the lowering of the flash pointof the lubricating oil 103 can be further effectively suppressed by theaddition of the fullerene.

The amount of the acid capturing agent and/or fullerene added as thestabilizing agent is only required to fall within a range of 0.1 to 4.0wt. % of the entire amount of the lubricating oil 103. By adjusting theamount of the stabilizing agent added (i.e., the content of thestabilizing agent) within the above range, the properties of thelubricating oil 103 can be improved by an appropriate amount ofstabilizing agent. Therefore, the reliability of the refrigerantcompressor 100 can be further improved.

As above, in the refrigerant compressor 100 according to the presentdisclosure, the electric element 106, the compression element 107, andthe like are accommodated in the sealed container 101, and thelubricating oil 103 is stored in the sealed container 101. Thelubricating oil 103 is the mixed oil constituted by at least the mineraloil and the synthetic oil. The kinetic viscosity of the lubricating oil103 at 40° C. falls within a range of 0.1 to 5.1 mm²/s, and the flashpoint of the lubricating oil 103 is 110° C. or more.

The base oil of the lubricating oil 103 is not the mineral oil but themixed oil constituted by the mineral oil and the synthetic oil. Whenmixing the mineral oil and the synthetic oil with each other, thekinetic viscosity is adjusted to fall within the above range, and thelower limit of the flash point is adjusted to become the above value.With this, the lubricating oil 103 having the low viscosity and the highflash point is obtained, and therefore, the deterioration of thehandleability of the lubricating oil 103 can be effectively suppressed.On this account, by using the lubricating oil 103, the efficiency of therefrigerant compressor 100 can be increased. In addition, even when thelubricating oil 103 having lower viscosity is used, the highproductivity can be realized.

In Embodiment 1, the refrigerant compressor 100 is configured such thatthe electric element 106 is arranged above the compression element 107.However, needless to say, the refrigerant compressor according to thepresent disclosure may be configured such that the electric element 106is arranged under the compression element 107. When a refrigerantcompressor to which the present disclosure is applicable is configuredto be able to use the above-described lubricating oil 103, suchrefrigerant compressor can obtain the same operational advantages asEmbodiment 1.

As described above, in Embodiment 1, the refrigerant compressor 100 isthe reciprocating type. However, needless to say, the refrigerantcompressor according to the present disclosure is not limited to thereciprocating type and may be a known type, such as a rotary type, ascroll type, or a vibration type. When a refrigerant compressor to whichthe present disclosure is applicable is configured to be able to use theabove-described lubricating oil 103, such refrigerant compressor canobtain the same operational advantages as Embodiment 1.

In Embodiment 1, the refrigerant compressor 100 is driven by acommercial power supply. However, the refrigerant compressor accordingto the present disclosure is not limited to this and may be, forexample, inverter-driven at a plurality of driving frequencies. Evenwhen the refrigerant compressor is configured as above, high lubricitycan be realized by using the above-described lubricating oil 103.Therefore, the reliability of the refrigerant compressor can be improvedeven at the time of low-speed driving in which the amount of oilsupplied to the respective slide portions becomes small or at the timeof high-speed driving in which the rotational frequency of the electricelement increases.

Embodiment 2

In Embodiment 2, one example of a refrigeration device including therefrigerant compressor 100 described in Embodiment 1 will bespecifically described with reference to FIG. 2. FIG. 2 schematicallyshows a schematic configuration of a refrigeration device 200 includingthe refrigerant compressor 100 according to Embodiment 1. Therefore,Embodiment 2 schematically describes a basic configuration of therefrigeration device 200. However, needless to say, the specificconfiguration of the refrigeration device 200 is not limited to this.

As shown in FIG. 2, the refrigeration device 200 according to Embodiment2 includes a main body 206, a partition wall 209, a refrigerant circuit201 (refrigeration cycle), and the like. The main body 206 isconstituted by a heat-insulation box body, a door body, and the like.The box body includes an opening on one surface thereof, and the doorbody opens and closes the opening of the box body. The inside of themain body 206 is divided by the partition wall 209 into a storage space207 for articles and a machine room 208. A blower (not shown) isprovided in the storage space 207. It should be noted that the inside ofthe main body 206 may be divided into, for example, spaces other thanthe storage space 207 and the machine room 208.

The refrigerant circuit 201 (refrigeration cycle) is configured to coolthe inside of the storage space 207 and includes, for example, therefrigerant compressor 100 described in Embodiment 1, a heat radiator202, a decompressor 203, and a heat absorber 204. The refrigerantcompressor 100, the heat radiator 202, the decompressor 203, and theheat absorber 204 are annularly connected to one another by a pipe 205.The heat absorber 204 is arranged inside the storage space 207. As shownby broken line arrows in FIG. 2, cooling heat of the heat absorber 204is stirred by the blower (not shown) so as to circulate in the storagespace 207. With this, the inside of the storage space 207 is cooled.

As above, the refrigeration device 200 according to Embodiment 2includes the refrigerant circuit 201 including the refrigerantcompressor 100 according to Embodiment 1. As described in Embodiment 1,the efficiency of the refrigerant compressor 100 is increased by usingthe lubricating oil 103 having the low viscosity and the high flashpoint. Therefore, the refrigeration device 200 according to Embodiment 2can reduce power consumption. On this account, energy saving can berealized, and reliability can be improved.

The refrigeration device 200 described in Embodiment 2 is one example ofthe refrigeration device according to the present disclosure (i.e., therefrigeration device including the refrigerant compressor according tothe present disclosure). Needless to say, the present disclosure is notlimited to the refrigeration device 200. Examples of the refrigerationdevice according to the present disclosure include refrigerators (homeuse, business use), dehumidifiers, showcases, ice makers, heat pumpwater heaters, heat pump washing/drying machines, vending machines, andair conditioners.

The present invention is not limited to the above described embodimentsand may be modified in various ways within the scope of the claims, andembodiments obtained by suitably combining technical means disclosed indifferent embodiments and/or plural modified examples are included inthe technical scope of the present invention.

From the foregoing explanation, many modifications and other embodimentsof the present invention are obvious to one skilled in the art.Therefore, the foregoing explanation should be interpreted only as anexample and is provided for the purpose of teaching the best mode forcarrying out the present invention to one skilled in the art. Thestructures and/or functional details may be substantially modifiedwithin the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is widely and suitably applicable to the field ofrefrigerant compressors using lubricating oil having low viscosity andrefrigeration device s including such refrigerant compressors.

REFERENCE SIGNS LIST

100 refrigerant compressor

101 sealed container

102 refrigerant gas

103 lubricating oil

104 stator

105 rotor

106 electric element

107 compression element

200 refrigeration device

201 refrigerant circuit

202 heat radiator

203 decompressor

204 heat absorber

205 pipe

1. A sealed refrigerant compressor comprising: a compression elementaccommodated in a sealed container and configured to compress arefrigerant; and an electric element configured to drive the compressionelement, wherein: lubricating oil is stored in the sealed container; thelubricating oil is mixed oil constituted by at least mineral oil andsynthetic oil; kinetic viscosity of the lubricating oil at 40° C. fallswithin a range of 0.1 to 5.1 mm²/s; and a flash point of the lubricatingoil is 110° C. or more.
 2. The sealed refrigerant compressor accordingto claim 1, wherein a content of the synthetic oil in the lubricatingoil falls within a range of 0.1 to 40.0 wt. % of an entire amount of thelubricating oil.
 3. The sealed refrigerant compressor according to claim1, wherein the synthetic oil is at least one selected from the groupconsisting of ester oil, ether oil, polyalkylene glycol oil, and alkylbenzene oil.
 4. The sealed refrigerant compressor according to claim 1,wherein at least one of additives that are an extreme pressure additive,an oily agent, an antifoaming agent, and a stabilizing agent is added tothe lubricating oil.
 5. The sealed refrigerant compressor according toclaim 4, wherein a content of the additive falls within a range of 0.1to 4.0 wt. % of the entire amount of the lubricating oil.
 6. The sealedrefrigerant compressor according to claim 1, wherein the lubricating oilhas a distillation property in which a distillation range is 200 to 400°C.
 7. A refrigeration device comprising the sealed refrigerantcompressor according to claim 1.